Boeing Vertol YUH-61
The Boeing Vertol YUH-61 (company designation Model 179), was a twin turbine-engined, medium-lift, military assault/utility helicopter. The YUH-61 was the runner-up in the United States Army Utility Tactical Transport Aircraft System (UTTAS) competition in the early 1970s to replace the Bell UH-1 Iroquois helicopter. At the end of the flyoff program, Sikorsky Aircraft was awarded a contract to develop and build its UH-60A entry. History Under a contract awarded in August 1972, Boeing Vertol designed and delivered three prototypes to compete UTTAS program.Gunston, Bill: The Illustrated Encyclopedia of the World's Modern Military Aircraft, page 205. Crescent Books, New York, NY USA, ca. 1978. ISBN 978-0-517-22477-9 When Boeing Vertol failed to win the Army competition, it pinned its hope on winning civil orders and the US Navy's LAMPS III program. In the end, a variant of the Sikorsky design, the SH-60B, won the Navy contract, and the civil orders received were canceled. Three aircraft were built and a further two were cancelled and not completed. An attack helicopter design, using the YUH-61's dynamic system was proposed for the Advanced Attack Helicopter competition, but did not make the downselect that resulted in the Bell YAH-63 and Hughes YAH-64 being built. The Boeing Vertol AAH design was unique in that the crew were seated in a laterally staggered tandem configuration.http://www.helis.com/h/bo_aah.jpg helis.com, Retrieved: June 14, 2011. Design The YUH-61 was designed to meet the UTTAS requirements for improved reliability, survivability and lower life-cycle costs, resulting in features such as dual-engines with improved hot and high altitude performance, and a modular design (reduced maintenance footprint); run-dry gearboxes; ballistically tolerant, redundant subsystems (hydraulic, electrical and flight controls); crashworthy crew (armored) and troop seats; dual-stage oleo main landing gear; ballistically tolerant, crashworthy main structure; quieter, more robust main and tail rotor systems; and a ballistically tolerant, crashworthy fuel system.Leoni 2007, pp. 42–48. Transport aboard the C-130 limited the UTTAS cabin height and length.Leoni 2007, pp. 39, 42–43. This also resulted in the main rotor being mounted very close to the cabin roof. While Sikorsky choose a fully articulated rotor head with elastomeric bearings, Boeing Vertol chose a rigid main rotor design, based upon technology supplied by MBB, which was partnered with Boeing Vertol at the time.Leoni 2007 Boeing Vertol also selected to use a tricycle landing gear and a pusher tail rotor, as opposed to the tail wheel configuration and canted tractor tail rotor that Sikorsky chose. Variants * Model 237: naval version of the YUH-61 for the USN's LAMPS II competition (ship-based multi-purpose helicopter) and lost out to Sikorsky SH-60 Seahawk; no models built * Model 179: civilian 14–20 passenger utility helicopter later canceled; 1 model built Survivors Two of the three aircraft (73-21656 and 73-21658) built are preserved at the United States Army Aviation Museum in Fort Rucker, Alabama. Specifications (YUH-61A) See also * Sikorsky S-70 * Sikorsky UH-60 Black Hawk * Sikorsky SH-60 Seahawk * List of helicopters *US Helicopter Armament Subsystems References ;Bibliography *Leoni, Ray D. Black Hawk, The Story of a World Class Helicopter. American Institute of Aeronautics and Astronautics, 2007. ISBN 978-1-56347-918-2. External links *UTTAS program—YUH-61 origins H-061 Boeing YUH-61 H-61, Boeing Category:1970s United States helicopters